Storage Battery (480) or Energy Storage System (706)

[ron]

I'm confused why the 2017 NEC developed Article 706 and didn't do a good job defining the difference between when it applies vs Article 480.

A UPS battery has used Article 480 in the past, but why not use 706 now?

Solar PV systems connected batteries have references specific to Energy Storage Systems Article 706, but it would seem that I could easily connect an Article 480 battery too.

Has anyone seen good narratives for this differentiation?

 

[tortuga]

Your not the only one, its pretty sloppy to have a battery and a cell defined twice in the code.

Looks both like 480 and 706 apply to UPS systems, and 706 will modify 480.
I think 480 should stick to battery equipment and 706 should stick to the interconnection of storage battery systems with other systems. I think 706 is kind of swerving into 480's lane so to speak.
For example 706.30(B) the 240V maximum for servicing should have been a 480 proposal.

The required diagram of power sources (706.11) is a welcome addition.
Theoretically 706 could apply to technology other than just traditional batteries?

 

[jaggedben]

706 covers much broader applications than 480 but I agree that the redundancy and vagueness is sloppy.

I can tell you that the impetus for 706 is the new products such as Powerwall and LG Chem batteries and similar that comprise a lot more than just a battery. But then, the same could have been said about a UPS before those came along.

I'm not aware of any good write ups on the issue.

 

[jaggedben]

... I think 706 is kind of swerving into 480's lane so to speak. For example 706.30(B) the 240V maximum for servicing should have been a 480 proposal.

Agreed.

Theoretically 706 could apply to technology other than just traditional batteries?

It's not theoretical, the 706 definitions of ESS are explicitly broader and include other examples such as capacitors and flywheels.